The proposed research is a 13C- and 19F-nmr study of heme-globin interaction and of conformation processes in the heme pocket which accompany ligand binding to hemoglobin. Hemes will be synthesized which are 13C enriched or 19F labeled specifically at the heme vinyl substituents. These molecules will be used as nmr probes to study the degree to which protein structure affects heme reactivity and the effects of heme ligation state on protein conformation in a mechanistically important region of the molecule.